Add trampolines for PTI support

Cargo.toml

src/arch/x86_64/interrupt/syscall.rs

src/arch/x86_64/macros.rs

src/arch/x86_64/mod.rs

src/arch/x86_64/pti.rs

src/arch/x86_64/start.rs

src/consts.rs

src/syscall/mod.rs

src/syscall/process.rs